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At least 1,585 records · Page 88Linked to original sources
USGS2007

Modeling environmental bias and computing velocity field from data of Terra Nova Bay GPS network in Antarctica by means of a quasi-observation processing approach

A semi-permanent GPS network of about 30 vertices has been installed at Terra Nova Bay (TNB) near Ross Sea in Antarctica. A permanent GPS station TNB1 based on an Ashtech Z-XII dual frequency P-code GPS receiver with ASH700936D_M Choke Ring Antenna has been mounted on a reinforced concrete pillar built on bedrock since October 1998 and has recorded continuously up to the present. The semi-permanent network has been routinely surveyed every summer using high quality dual frequency GPS receivers with 24 hour sessions at 15 sec rate; data, metadata and solutions will be available to the scientific community at (http://www.geodant.unimore.it). We present the results of a distributed session approach applied to processing GPS data of the TNB GPS network, and based on Gamit/Globk 10.2-3 GPS analysis software. The results are in good agreement with other authors' computations and with many of the theoretical models.

Open-File Report↗
USGS2013

Use of Normalized Difference Vegetation Index (NDVI) habitat models to predict breeding birds on the San Pedro River, Arizona

Successful management practices of avian populations depend on understanding relationships between birds and their habitat, especially in rare habitats, such as riparian areas of the desert Southwest. Remote-sensing technology has become popular in habitat modeling, but most of these models focus on single species, leaving their applicability to understanding broader community structure and function largely untested. We investigated the usefulness of two Normalized Difference Vegetation Index (NDVI) habitat models to model avian abundance and species richness on the upper San Pedro River in southeastern Arizona. Although NDVI was positively correlated with our bird metrics, the amount of explained variation was low. We then investigated the addition of vegetation metrics and other remote-sensing metrics to improve our models. Although both vegetation metrics and remotely sensed metrics increased the power of our models, the overall explained variation was still low, suggesting that general avian community structure may be too complex for NDVI models.

Arizona↗
USGS1972

Travel time for solutes, upper Sabine River basin, Texas, April 16-30, 1972

The U.S. Geological Survey, in cooperation with the Sabine River Compact Administration, conducted time-of-travel studies in the Sabine River Basin on April 16-30, 1972. One study was made on the main stem of the Sabine River in four reaches from Lake Tawakoni to Toledo Bend Reservoir, a distance of 219 miles. Two other studies were made on reaches of Lake Fork Creek and Big Sandy Creek. The purpose of these studies was to provide travel-rate data to be used by the Sabine River Authority of Texas in constructing a hydrologic model of the basin.

Texas↗
USGS1979

Derivation of homogeneous streamflow records for the Green River basin, Kentucky

Four flood-control reservoirs, Green River Lake, Nolin River Lake, Barren River Lake, and Rough River Lake, were completed in the Green River basin of Kentucky between 1959 and 1969. A digital computer model of these reservoirs and the stream reaches from the reservoirs downstream to the Green River at Calhoun, Ky., was developed to simulate mean daily streamflows. Simulations of 1941 through 1971 water year streamflows were made for both the pre-reservoir and post-reservoir basin conditions, thus supplying homogeneous data sets for low-flow analyses of eight stream sites. The 7-day, 10-year recurrence interval, minimum discharges of the simulated regulated flows exceed those of the simulated natural flows by about 30 cubic feet per second for the Barren River at Bowling Green, Ky., and about 260 cubic feet per second for the Green River at Calhous, Ky. Analyses of the pre-reservoir simulations show that, for seven of the stream sites, the model yields streamflow which have annual minimum 7-day average discharges that are not significantly different, at the 95 percent significance level, from those of the observed flows. Results of the post-reservoir simulations show that actual reservoir operation was not closely matched by the model. Therefore, the low-flow characteristics of the simulated regulated streamflows are merely estimates of those that could be expected if the basin were regulated according to the modeled reservoir operating criteria. (USGS)

Open-File Report↗
USGS1979

Radium and uranium concentrations and associated hydrogeochemistry in ground water in southwestern Pueblo County, Colorado

Radium and uranium concentrations in water from 37 wells tapping the aquifer system of the Dakota Sandstone and Purgatoire Formation in southwestern Pueblo County, Colorado, have a wide range of values and define several areas of high radioactivity in the ground water. Radium ranges from 0.3 to 420 picocuries per liter and has a median value of 8.8, and uranium ranges from 0.02 to 180 micrograms per liter and has a median value of 2.4. Radon concentrations, measured in 32 of the 37 wells, range from less than 100 picocuries per liter to as much as 27,000 and have a median value of 580. Relationships among the radioactive elements and 28 other geochemical parameters were studied by using correlation coefficients and R-mode factor analysis. Five factor groups were determined to represent major influences on water chemistry: (1) short-term solution reactions, (2) oxidation reactions, (3) hydrolysis reactions, (4) uranium distribution, and (5) long-term solution reactions. Uranium concentrations are most strongly influenced by oxidation reactions but also are affected by solution reactions and distribution of uranium in the rocks of the aquifer system. Radon and radium concentrations are mostly controlled by uranium distribution; radium also shows a moderate negative relationship with oxidation. To explain the statistical and spatial relationships among the parameters, a model was developed involving the selective leaching of uranium-bearing phases and metal sulfides which occur in discontinuous zones in sandstone and shale. When reducing conditions prevail, uranium is immobile, but radium can be taken into solution. When faults and associated fractured rocks allow oxidizing conditions to dominate, uranium can be taken into solution; radium can also be taken into solution, or it may become immobilized by coprecipitation with iron and manganese oxides or with barite. Several areas within the study area are discussed in terms of the model.

Open-File Report↗
USGS1984

Glacial aquifer systems in the northeastern United States; a plan for study

The U.S. Geological Survey project designed to study the availability and quality of water in glacial aquifers in the States of Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, Connecticut, New York, New Jersey, Pennsylvania, and Ohio is scheduled for completion in 1986. It will focus on general principles that define aquifer geometry, hydraulic properties of sediments, recharge, discharge, physical-chemical properties of water, rock and water-rock interactions, and mechanisms for mixing of water from multiple sources. Planned project activities include compilation and analysis of available data for a regionwide analysis of glacial-aquifer systems, studies of selected system components such as recharge and chemical processes, classification of aquifers with regard to water-supply potential, and construction of generalized ground-water models to predict responses of types of aquifer systems to pumping and climatic stress. This report describes the general characteristics of glacial aquifer systems in the Northeastern United States and of planned work elements of the study. (USGS)

Open-File Report↗
USGS1985

Ground-water quality data from the northern Mississippi embayment: Arkansas, Missouri, Kentucky, Tennessee, and Mississippi

Forty-five analyses of ground-water quality from 42 selected wells in the McNairy-Nacatoch-Ripley and lower Wilcox aquifers of the northern Mississippi embayment have been compiled as part of the Gulf Coast Regional Aquifer System Analysis (RASA) project of the U.S. Geological Survey. Thirty-seven wells were sampled during the period October 1983 to September 1984 specifically for this RASA study; three of these wells were sampled twice. Five wells were sampled during the period January 1981 to March 1985 for other projects. All 45 analyses are included herein as a single data base that will be used for geochemical modeling of mineral saturation and mass transfer in the McNairy-Nacatoch-Ripley aquifer. The report contains two figures, six tables of data, and a brief documentation of the methods used for sample collection and analysis. The figures are maps showing locations of sampling sites for each of the two aquifers. The tables of data include (1) well descriptions and (2) concentrations of major constituents, trace constituents, dissolved gases, stable and unstable isotopes of low mass (C, H, 0, and S>, and unstable isotopes of high mass (Rn, Ra, and U).

Arkansas, Kentucky, Mississippi, Missouri, Tenness↗
USGS1996

Numerical model analysis of the effects of ground-water withdrawals on discharge to streams and springs in small basins typical of the Puget Sound Lowland, Washington

A numerical ground-water flow model of a hypothetical basin was constructed and used to investigate the effects of ground-water withdrawals on rates of natural discharge to streams and springs in small basins of the Puget Sound Lowland. Definitions of the topography, geology, drainage, and climate of the hypothetical basin were based on the features of typical small basins in the Puget Sound Lowland. This information was used to construct a 13-layer numerical ground-water flow model capable of simulating water levels, hydraulic gradients, and discharge to streams and springs. Three sequences of glacial drift and interglacial deposits were simulated in the model; each sequence consisted of recessional outwash, till, advance, outwash, and fine-grained interglacial sediments. Alluvial sediments of the major stream valleys and undifferentiated glacial and interglacial deposits were also included in the model. The model was calibrated by comparing simulated hydrologic conditions with expected conditions and making adjustments to values of hydraulic characteristics as needed. The model was calibrated to predevelop- ment conditions (those prior to pumping), and then used to simulate the effects of pumping on natural discharge to streams and springs. Seven series of simulations were made to investigate the effects of (1) distance from the well to a stream, (2) the presence of confining layers, (3) pumping rate, (4) depth of the pumped aquifer, (5) distance from the well to a bluff, (6) well density, and (7) recharge rate. The discharge of wells pumping from unconfined outwash aquifers on the drift plains is derived almost entirely from capture of natural discharge to nearby stream reaches. Increasing the lateral distance between the well and stream caused more of the well discharge to be captured from other streams on the drift plain. Pumping from aquifers separated from the stream by one or more confining layers caused a reduction in the effects of pumping on discharge to nearby streams that was offset by an increase in the effects on discharge to more distant streams and springs. The percentage of well discharge captured from springs on the bluff was sensitive to the distance of wells from the bluff. Simulations also showed that increased well density caused greater water-level decline locally, but, at equilibrium, did not affect the extent of the area affected by reduction of natural discharge to streams and springs. Finally, decreased recharge in areas where development had created impervious surfaces had a direct effect on the natural discharge rates to streams and springs. Increased recharge, however, increased natural discharge and offset the effects of well withdrawals. Further analysis of the time-dependent effects of with- drawals would provide additional insights, but would require the development of a transient version of the model.

Open-File Report↗
USGS1999

Digital data used to relate nutrient inputs to water quality in the Chesapeake Bay watershed

Digital data sets were compiled by the U. S. Geological Survey (USGS) and used as input for a collection of Spatially Referenced Regressions On Watershed attributes for the Chesapeake Bay region. These regressions relate streamwater loads to nutrient sources and the factors that affect the transport of these nutrients throughout the watershed. A digital segmented network based on watershed boundaries serves as the primary foundation for spatially referencing total nitrogen and total phosphorus source and land-surface characteristic data sets within a Geographic Information System. Digital data sets of atmospheric wet deposition of nitrate, point-source discharge locations, land cover, and agricultural sources such as fertilizer and manure were created and compiled from numerous sources and represent nitrogen and phosphorus inputs. Some land-surface characteristics representing factors that affect the transport of nutrients include land use, land cover, average annual precipitation and temperature, slope, and soil permeability. Nutrient input and land-surface characteristic data sets merged with the segmented watershed network provide the spatial detail by watershed segment required by the models. Nutrient stream loads were estimated for total nitrogen, total phosphorus, nitrate/nitrite, amonium, phosphate, and total suspended soilds at as many as 109 sites within the Chesapeake Bay watershed. The total nitrogen and total phosphorus load estimates are the dependent variables for the regressions and were used for model calibration. Other nutrient-load estimates may be used for calibration in future applications of the models.

Open-File Report↗
USGS2012

Baseline and projected future carbon storage and greenhouse-gas fluxes in ecosystems of the Western United States

This assessment was conducted to fulfill the requirements of section 712 of the Energy Independence and Security Act (EISA) of 2007 and to improve understanding of carbon and greenhouse gas (GHG) fluxes in ecosystems of the Western United States. The assessment examined carbon storage, carbon fluxes, and other GHG fluxes (methane and nitrous oxide) in all major terrestrial ecosystems (forests, grasslands/shrublands, agricultural lands, and wetlands) and aquatic ecosystems (rivers, streams, lakes, reservoirs, and coastal waters) in two time periods: baseline (generally in the first half of the 2010s) and future (projections from baseline to 2050). The assessment was based on measured and observed data collected by the U.S. Geological Survey (USGS) and many other agencies and organizations and used remote sensing, statistical methods, and simulation models.

Arizona;California;Colorado;Idaho;Montana;Nevada;N↗
USGS2009

Maps Showing Seismic Landslide Hazards in Anchorage, Alaska

The devastating landslides that accompanied the great 1964 Alaska earthquake showed that seismically triggered landslides are one of the greatest geologic hazards in Anchorage. Maps quantifying seismic landslide hazards are therefore important for planning, zoning, and emergency-response preparation. The accompanying maps portray seismic landslide hazards for the following conditions: (1) deep, translational landslides, which occur only during great subduction-zone earthquakes that have return periods of =~300-900 yr; (2) shallow landslides for a peak ground acceleration (PGA) of 0.69 g, which has a return period of 2,475 yr, or a 2 percent probability of exceedance in 50 yr; and (3) shallow landslides for a PGA of 0.43 g, which has a return period of 475 yr, or a 10 percent probability of exceedance in 50 yr. Deep, translational landslide hazard zones were delineated based on previous studies of such landslides, with some modifications based on field observations of locations of deep landslides. Shallow-landslide hazards were delineated using a Newmark-type displacement analysis for the two probabilistic ground motions modeled.

Scientific Investigations Map↗
USGS2004

Atlas of depth-duration frequency of precipitation annual maxima for Texas

Ninety-six maps depicting the spatial variation of the depth-duration frequency of precipitation annual maxima for Texas are presented. The recurrence intervals represented are 2, 5, 10, 25, 50, 100, 250, and 500 years. The storm durations represented are 15 and 30 minutes; 1, 2, 3, 6, and 12 hours; and 1, 2, 3, 5, and 7 days. The maps were derived using geographically referenced parameter maps of probability distributions used in previously published research by the U.S. Geological Survey to model the magnitude and frequency of precipitation annual maxima for Texas. The maps in this report apply that research and update depth-duration frequency of precipitation maps available in earlier studies done by the National Weather Service.

Scientific Investigations Report↗
USGS2010

Implementation of local grid refinement (LGR) for the Lake Michigan Basin regional groundwater-flow model

The U.S. Geological Survey is evaluating water availability and use within the Great Lakes Basin. This is a pilot effort to develop new techniques and methods to aid in the assessment of water availability. As part of the pilot program, a regional groundwater-flow model for the Lake Michigan Basin was developed using SEAWAT-2000. The regional model was used as a framework for assessing local-scale water availability through grid-refinement techniques. Two grid-refinement techniques, telescopic mesh refinement and local grid refinement, were used to illustrate the capability of the regional model to evaluate local-scale problems. An intermediate model was developed in central Michigan spanning an area of 454 square miles (mi2) using telescopic mesh refinement. Within the intermediate model, a smaller local model covering an area of 21.7 mi2 was developed and simulated using local grid refinement. Recharge was distributed in space and time using a daily output from a modified Thornthwaite-Mather soil-water-balance method. The soil-water-balance method derived recharge estimates from temperature and precipitation data output from an atmosphere-ocean coupled general-circulation model. The particular atmosphere-ocean coupled general-circulation model used, simulated climate change caused by high global greenhouse-gas emissions to the atmosphere. The surface-water network simulated in the regional model was refined and simulated using a streamflow-routing package for MODFLOW. The refined models were used to demonstrate streamflow depletion and potential climate change using five scenarios. The streamflow-depletion scenarios include (1) natural conditions (no pumping), (2) a pumping well near a stream; the well is screened in surficial glacial deposits, (3) a pumping well near a stream; the well is screened in deeper glacial deposits, and (4) a pumping well near a stream; the well is open to a deep bedrock aquifer. Results indicated that a range of 59 to 50 percent of the water pumped originated from the stream for the shallow glacial and deep bedrock pumping scenarios, respectively. The difference in streamflow reduction between the shallow and deep pumping scenarios was compensated for in the deep well by deriving more water from regional sources. The climate-change scenario only simulated natural conditions from 1991-2044, so there was no pumping stress simulated. Streamflows were calculated for the simulated period and indicated that recharge over the period generally increased from the start of the simulation until approximately 2017, and decreased from then to the end of the simulation. Streamflow was highly correlated with recharge so that the lowest streamflows occurred in the later stress periods of the model when recharge was lowest.

Scientific Investigations Report↗
USGS2011

Evaluation of LiDAR-acquired bathymetric and topographic data accuracy in various hydrogeomorphic settings in the Deadwood and South Fork Boise Rivers, West-Central Idaho, 2007

High-quality elevation data in riverine environments are important for fisheries management applications and the accuracy of such data needs to be determined for its proper application. The Experimental Advanced Airborne Research LiDAR (Light Detection and Ranging)-or EAARL-system was used to obtain topographic and bathymetric data along the Deadwood and South Fork Boise Rivers in west-central Idaho. The EAARL data were post-processed into bare earth and bathymetric raster and point datasets. Concurrently with the EAARL surveys, real-time kinematic global positioning system surveys were made in three areas along each of the rivers to assess the accuracy of the EAARL elevation data in different hydrogeomorphic settings. The accuracies of the EAARL-derived raster elevation values, determined in open, flat terrain, to provide an optimal vertical comparison surface, had root mean square errors ranging from 0.134 to 0.347 m. Accuracies in the elevation values for the stream hydrogeomorphic settings had root mean square errors ranging from 0.251 to 0.782 m. The greater root mean square errors for the latter data are the result of complex hydrogeomorphic environments within the streams, such as submerged aquatic macrophytes and air bubble entrainment; and those along the banks, such as boulders, woody debris, and steep slopes. These complex environments reduce the accuracy of EAARL bathymetric and topographic measurements. Steep banks emphasize the horizontal location discrepancies between the EAARL and ground-survey data and may not be good representations of vertical accuracy. The EAARL point to ground-survey comparisons produced results with slightly higher but similar root mean square errors than those for the EAARL raster to ground-survey comparisons, emphasizing the minimized horizontal offset by using interpolated values from the raster dataset at the exact location of the ground-survey point as opposed to an actual EAARL point within a 1-meter distance. The average error for the wetted stream channel surface areas was -0.5 percent, while the average error for the wetted stream channel volume was -8.3 percent. The volume of the wetted river channel was underestimated by an average of 31 percent in half of the survey areas, and overestimated by an average of 14 percent in the remainder of the survey areas. The EAARL system is an efficient way to obtain topographic and bathymetric data in large areas of remote terrain. The elevation accuracy of the EAARL system varies throughout the area depending upon the hydrogeomorphic setting, preventing the use of a single accuracy value to describe the EAARL system. The elevation accuracy variations should be kept in mind when using the data, such as for hydraulic modeling or aquatic habitat assessments.

Idaho↗
USGS2014

Approaches for evaluating the effects of bivalve filter feeding on nutrient dynamics in Puget Sound, Washington

Marine bivalves such as clams, mussels, and oysters are an important component of the food web, which influence nutrient dynamics and water quality in many estuaries. The role of bivalves in nutrient dynamics and, particularly, the contribution of commercial shellfish activities, are not well understood in Puget Sound, Washington. Numerous approaches have been used in other estuaries to quantify the effects of bivalves on nutrient dynamics, ranging from simple nutrient budgeting to sophisticated numerical models that account for tidal circulation, bioenergetic fluxes through food webs, and biochemical transformations in the water column and sediment. For nutrient management in Puget Sound, it might be possible to integrate basic biophysical indicators (residence time, phytoplankton growth rates, and clearance rates of filter feeders) as a screening tool to identify places where nutrient dynamics and water quality are likely to be sensitive to shellfish density and, then, apply more sophisticated methods involving in-situ measurements and simulation models to quantify those dynamics.

Washington↗
USGS2017

Three-dimensional hydrogeologic framework model of the Rio Grande transboundary region of New Mexico and Texas, USA, and northern Chihuahua, Mexico

As part of a U.S. Geological Survey study in cooperation with the Bureau of Reclamation, a digital three-dimensional hydrogeologic framework model was constructed for the Rio Grande transboundary region of New Mexico and Texas, USA, and northern Chihuahua, Mexico. This model was constructed to define the aquifer system geometry and subsurface lithologic characteristics and distribution for use in a regional numerical hydrologic model. The model includes five hydrostratigraphic units: river channel alluvium, three informal subdivisions of Santa Fe Group basin fill, and an undivided pre-Santa Fe Group bedrock unit. Model input data were compiled from published cross sections, well data, structure contour maps, selected geophysical data, and contiguous compilations of surficial geology and structural features in the study area. These data were used to construct faulted surfaces that represent the upper and lower subsurface hydrostratigraphic unit boundaries. The digital three-dimensional hydrogeologic framework model is constructed through combining faults, the elevation of the tops of each hydrostratigraphic unit, and boundary lines depicting the subsurface extent of each hydrostratigraphic unit. The framework also compiles a digital representation of the distribution of sedimentary facies within each hydrostratigraphic unit. The digital three-dimensional hydrogeologic model reproduces with reasonable accuracy the previously published subsurface hydrogeologic conceptualization of the aquifer system and represents the large-scale geometry of the subsurface aquifers. The model is at a scale and resolution appropriate for use as the foundation for a numerical hydrologic model of the study area.

Chihuahua, New Mexico, Texas↗
USGS2022

Virginia Bridge Scour Pilot Study—Hydrological Tools

Hydrologic and geophysical components interact to produce streambed scour. This study investigates methods for improving the utility of estimates of hydrologic flow in streams and rivers used when evaluating potential pier scour over the design-life of highway bridges in Virginia. Recent studies of streambed composition identify potential bridge design cost savings when attributes of cohesive soil and weathered rock unique to certain streambeds are considered within the bridge planning design. To achieve potential cost savings, however, attributes and effects of scour forces caused by water movement across the streambed surface must be accurately described and estimated. This study explores the potential for improving estimates of the hydrologic component, namely hydrologic flow, afforded by empirically based deterministic, probabilistic, and statistical modeling of flows using streamgage data from 10 selected sites in Virginia. Methods are described and tools are provided that may assist with estimating hydrological components of flow duration and potential cumulative stream power for bridge designs in specific settings, and calculation of comprehensive projections of anticipated individual bridge pier scour rates. Examples of hydrologic properties needed to determine the rates of streambed scour are described for sites spanning a range of basin sizes and locations in Virginia. Deterministic, probabilistic, and statistical modeling methods are demonstrated for estimating hydrological components of streambed scour over a bridge design lifespan. Eight tools provide examples of streamflow analysis using daily and instantaneous streamflow data collected at 10 study sites in Virginia. Tool 1 provides a generalized system dynamics model of streamflow and sediment motion that may be used to estimate hydrologic flow over time. Tool 2 illustrates at-a-station hydraulic geometry using methods pioneered by Leopold and others. Tool 3 provides a system dynamics model developed to test the use of Monte-Carlo sampling of instantaneous streamflow measurements to augment and increase precision of site-specific period-of-record daily-flow values useful for driving stream-power and streambed scour estimates. Tool 4 integrates deterministic modeling, maximum likelihood logistic regression, and Monte-Carlo sampling to identify probable hydrologic flows. Tool 5 provides instantaneous flow hydrologic envelope profiles, using measured instantaneous flow data integrated with measured daily-flow value data. Tool 6 provides precise estimates of hydrologic flow over entire data time-series suitable for driving scour simulation models. Tool 7 provides a threshold of flow and probability of time-under-load interactive calculator that allows selection of a desired bridge design lifespan, ranging from 1 to 250 years, and identification of a flow interval of interest. Tool 8 provides a flow-random sampling interactive tool, developed to facilitate easy access to large datasets of randomly sampled flow data measurements from unique locations for purposes of computing and testing future models of bridge pier scour.

Virginia↗
USGS2020

Elevation-derived hydrography acquisition specifications

Hydrographic features derived from U.S. Geological Survey (USGS) 3D Elevation Program data, and collected for use by the USGS, must meet the specifications described in this document. The specifications described herein pertain to the final product delivered to the USGS, not to methods used to derive the hydrographic features. The specifications describe the collection area, spatial reference system, attribute table structure, feature codes and values, delineation of hydrographic features, topology, positional assessment, metadata, and delivery formats. A companion document, Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules, defines the fields, domains, and minimum feature collection requirements for hydrography features derived from elevation data. Hydrographic features collected to this specification will be suitable for using as breaklines to hydroflatten digital elevation models, processing for preconflation of features to the National Hydrography Dataset, and using for hydroenforcement of digital elevation models.

Techniques and Methods↗